Various types of filtration devices are known and employed in the filter industry. Canister-type filters are, typically, used for removing particulate matter from lubricating oils in vehicles and other machinery. Such filters are attached to the vehicle or machine to continuously filter the oil while the machine is operating.
Canister-type filters which are used on motor vehicle engines, while being able to operate satisfactorily for a period of time, lose efficiency as time passes and particulate matter builds up on the filter medium. They must, therefore, be discarded and replaced after approximately 100 to 300 hours of use.
Canister-type filters can also be employed for filtration of particulate matter from water. Such filters can be used in homes and industry for removing sand, grit, rust, and water treatment chemicals from water supplies. Use of such filters is particularly appropriate in rural homes where the water supply has a high concentrate of particulate deposits.
Again, however, the useful life of the filter is limited by the rate at which clogging occurs. As clogging increases, the pressure drop across the filter medium increases commensurately.
A significant problem in the filtration industry has, therefore, been this residual build-up of filtered particulates on the filter medium. Because of the typical surface area of filtration medium elements, little storage capacity is afforded. A relatively short component life, thereby, results.
One solution which has been attempted and which has gone far to resolving these problems is a self-cleaning fluid filter as disclosed in Applicant's prior patent, U.S. Pat. No. 4,645,591, which issued on Feb. 24, 1987. The device of that document, while being able to filter various fluids, was particularly intended for use in vehicle lubrication system filtration. The canister housing of the filter device disclosed in that document employed means for mating the filter with a nipple of the face of the engine with which it is intended to be used.
As previously indicated, that invention was a significant advance over the prior art. The housing defined a sump into which particulate build-up on the filter medium, purged during initial start-up of the engine, was deposited. Consequently, the problem of the limited surface area of the filter medium was overcome. this, in turn, extended the use of the filter.
Still, however, the life of the filter was limited, although to a lesser extent than in prior art devices, because of the limited capacity of the sump. While the presence of the sump significantly multiplies useful life of a device constructed in accordance with that patent, eventually, the sump becomes filled, and the filter canister must be discarded.
Additionally, the particular design employed in the device illustrated in that patent was relatively complicated in operation. Further, the filter illustrated in that document provided certain safeguards which are, typically, necessary in a filtration system such as in a motor vehicle. In a constant pressure system, such as a water supply of a municipality, certain of those safeguards are unnecessary.
The present invention is an improvement over prior art filters including Applicant's invention as disclosed in his U.S. Pat. No. 4,645,591. It provides a filtration mechanism which is simple in both its construction and operation. Additionally, however, it provides a filter which has a virtually unlimited operational life.